1. Field of the Invention
This invention relates to an endoscope which can be used for various purposes such as medical and industrial purposes, and an attaching method of connection mouth ring to an end of an endoscopic flexible tube.
2. Description of the Related Art
Heretofore, in manufacturing a flexible tube (flexible tube) used for an insertion portion or a universal cable of an endoscope, generally, a connection mouth ring has been fixed by adhesive bonding to a portion (hard portion) where a helical tube and a braid tube are braze-welded. However, braze welding requires a subsequent flux cleaning process, and the adhesive bonding requires time to complete the drying.
Thus, for example, Jpn. Pat. Appln. KOKAI Publication No. S57-171311 has disclosed a method of internally and externally clamping a braid tube between two connection mouth rings. This method can be applied to clamp all three layers forming a flexible tube which include a helical tube, a braid tube and a flexible outer tube between two connection mouth rings from the inside and outside of the flexible tube. If this method is used, the flexible tube can be cut at any part to attach the connection mouth ring in the final manufacturing process of the flexible tube, which permits a stable total length at completion.
In order to carry out such a method, a core bar is inserted through the inner connection mouth ring to prevent the diametrical reduction of the inner connection mouth ring, in which state the outer connection mouth ring is tightened (caulked) and plastically deformed.